Poly(arylene sulfide ketone)s, henceforth PASK, and poly(arylene sulfide diketone)s, henceforth PASDK, are engineering thermoplastics of potential commercial interest for film, fiber, molding, and composite applications because of their high melting points and high heat resistance. General processes for the production of PASK and PASDK are known in the art.
One disadvantage often associated with the preparation of PASK and PASDK resins pertains to the resins' thermal stability. Specifically, PASK and PASDK resins are generally plagued by having associated therewith relatively low thermal stabilities. When either PASK or PASDK resins are prepared and recovered by conventional methods, the resins contain volatile by-product materials. These volatiles often show their presence when the resins are heated to a temperature of at least about 315.degree. C. (600.degree. F.). Since many subsequent polymer processing procedures (e.g., melt-forming, extrusion and blow-molding) often require that the resin be heated to a temperature above its melting point, and since both PASK and PASDK resins have melting points above about 315.6.degree. C. (600.1.degree. F.), the subsequent melt-processing of PASK and PASDK resins results in these volatiles vaporizing and/or boiling through the polymeric resin, thus, leaving voids therethrough. This vaporization of volatile materials is commonly known in the polymer industry as "degassing" and/or "out-gassing". One detrimental effect of this degassing phenomena is that of decreasing the melt stability of the PASK and PASDK resins. Since high melt stability is a necessary characteristic of resins which are to be melt processed, a low melt stability makes melt-processing procedures very difficult, if not impossible.
Melt-processing PASK or PASDK resins in a manner which results in a substantially void-free product has many inherent commercial applications. Therefore, it would be most desirable to produce melt stable PASK or PASDK resins of good polymer quality. Moreover, melt stable PASK and PASDK resins would also have associated therewith improved processability, color, texture, flexibility, and/or toughness. Accordingly, an object of this invention is to provide a method for preparing and recovering melt stable PASK or PASDK resins.
Another object of this invention is to provide a method for melt-processing PASK and/or PASDK resins to form final products having improved color, texture, flexibility and/or toughness.
Other objects concepts and aspects of this invention will be apparent to those skilled in the art upon reading the following Detailed Description and appended claims.